Field of the Invention
The invention relates to a device for stripping material from a conveyor belt of a belt conveyor in a region of a curve of a discharge drum, below a discharge point of the belt conveyor, having a stripping body which is of one-part or multi-part configuration and is provided with a carrying element formed by a cable and/or a wire and/or a metal chain, by means of which the stripping body is or can be pulled against the conveyor belt, and having a fastening device and a tensioning device for the carrying element, wherein in the installed state the carrying element is arranged so that it encloses an acute angle (installation angle) with a straight line extending parallel to the axis of rotation of the discharge drum, and at one of its ends it is connected to the fastening device and at its other end it is connected to the tensioning device, wherein the tensioning device has a spring, preferably a helical spring, a stop for supporting the spring and a traction rod, and wherein the traction rod is connected to the carrying element and has a thread which is provided with a nut or a screw having a head.
Moreover, the invention relates to a method for installing a stripping device for stripping material from a conveyor belt of a belt conveyor in the region of the curve of a discharge drum, below the discharge point of the belt conveyor, wherein the stripping device has a stripping body which is of one-part or multi-part configuration and is provided with a carrying element formed by a cable and/or a wire and/or a metal chain, and at one of its ends it is connected to the fastening device and at its other end it is connected to the tensioning device, wherein the carrying element is arranged so that it encloses an acute angle with a straight line extending parallel to the axis of rotation of the discharge drum, wherein the tensioning device has a spring, preferably a helical spring, a stop for supporting the spring and a traction rod, wherein the traction rod is connected to the carrying element and has a thread which is provided with a nut or a screw having a head, and wherein by turning the nut screwed to the traction rod or the screw the carrying element is tensioned in order to pull the stripping body against the conveyor belt.
Description of Related Art
Such stripping devices are known for example from US 2004/0222065 A1 and EP 2 257 486 B1. In this case the stripping body is installed as a pre-head stripper directly below the discharge region of the belt conveyor. The stripping body is typically tensioned obliquely over the head drum (discharge drum) and thus extends along a three-dimensional curve.
The stripping devices according to the prior art which are configured in this way are designed for a specific installation position, in which the longitudinal axis of the stripping body or its tensionable carrying element, for example a wire cable, encloses a specific angle of inclination (installation angle) with a straight line extending parallel to the axis of rotation of the discharge drum. Since the effectiveness of the stripping body is dependent upon the tensile force (pretension), the associated installation instructions recommend the setting of a specific tensile force. In practice, however, it has been shown that the effectiveness or functioning of the stripping device is sometimes unsatisfactory, even though the tensile force, for example 2700 N, recommended in the installation instructions has been set.
The applicant has recognised that as a consequence of the setting of a specified tensile force the pressing force of the stripping body or the stripping elements provided thereon, for example hard metal elements, varies significantly depending upon the installation position and is frequently too high. The consequence of this, in particular in the case of strongly adhering, abrasive material to be conveyed, is that the stripping body wears too quickly and/or that grooves of unacceptable depth are produced in the surface of the conveyor belt by the scraping effect of the hard metal elements. Such damage can potentially lead to the conveyor belt becoming unusable and having to be replaced at considerable expense.
In view of the fact that the pressing force of the stripping body must have a defined magnitude, so that on the one hand a good stripping result is achieved and on the other hand the wear on the stripper and on the conveyor belt is minimised, the tensioning force exerted on the carrying element or the stripping body must be variable and the tensile force necessary in this connection must be known and adjustable as a function of the discharge drum diameter, the size of the stripper contact surface and in particular the installation angle, in order to obtain the most uniform possible pressing forces of the stripping body or the stripping elements provided thereon, for example hard metal elements. In this connection the type of material to be conveyed plays rather an insignificant role here, since it is only the consistency of the material to be conveyed that can make a slight change to the tensile force necessary if the stripping result is insufficient.